Yeah, who has it, I'd like to have that too since my ported version doesn't work reliably.
I'm not sure if I understand the "custom board" thing exactly but I think it's just a SOPC system set up for the sole purpose of burning flash. I ported the flash programmer to our hardware (pin assignments, mainly) and rebuilt our actual design with the ported flash programmer as a target. After that I never touched the flash programmer again and I think that's the general idea.
